Sparking plug for internal-combustion engines and method of manufacturing the same



C. E. GERBAUI'J. SPARKINGPLUG FOR INTERNAL COMBUSTION ENGINES AND METHODOF MANUFACTURING THE SAME.

APPLICATION FILED FEB. 24, I9l9.

Patented July 20, 1920.

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w \6 LIE M WW 7 m? y B w W C A C. E. GERBAUD. SPARKING PLUG FOR INTERNALCOMBUS APPLICATION FILED FEB. 24, I919. 1,347, 367, Patented July 20,1920.

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Kin? f TION ENGINES AND METHOD OF MANUFACTURING THE SAME.

- UNITED STATES PATENT OFFICE.

CHARLES EMILE GERBAUD, OF PARIS, FRANCE;

SPARRING PLUG m INTERNAL-COMBUSTIONENGINES AND mnrnon or mum- FACTURINGTHE sun.

Specification of Letters Patent.

Patented July 20,1920.

Application filed February 24, 1919. Serial No. 278,694.

leakage of gas or lubricating oil.

A further object of this invention is to provide a plug capable ofwithstanding very great temperature and very heavy pressure, whilealways remaining completely insulated.

The characteristic features of my 1mproved plug (which is made in themanner hereinafter described) are:

1. The insulating body cast on to the central rod forming the axialelectrode, and

2. The metallic shell formed of a mass of metal cast on to saidinsulating body.

Figure 1 of the accompanying drawing shows, in central vertical sectionand by way of example, one form of the single-piece plug. I

Figs. 2 and 8 illustrate the mold in which the insulating body is cast,Fig. 2 being an elevation of the inner face of one half of the mold, theinsulating body being shown in section, while Fig. 3 is a plan of themold.

' Figs. 4 and 5 represent the mold in which the metallic shell is cast,Fig. 4 showing the inner face of one half of the mold, the metallicshell being shown in section, while Fig. 5 is a plan of the mold.

As is shown in Fig. 1, my improved plug comprises an axial rod a of theusual form, constituting one of the electrodes, an insulating body I)cast on said rod, and a metallic shell or body a cast on the insulatingbody.

The insulating body I) may be made of sodium boro-silicate of thefollowing comample, and that any other composition or lnsulatmg materialmay, if desired, be used.

The shell 0 is formed of a metal or metalllc alloy, which can be readilypoured, say, an alloy having the composition z zinc 75%; aluminium 15%;copper 10%.

The plug is made as follows:

The .rod or, intended to serve as the axial electrode, is placed in ametal mold, similar to the molds used in glass making, (consisting oftwo shells d hinged togetherFigs. 2 and 3and provided with an internalcavity corresponding in shape to the shape desired for the insulatingbody 1)), and, when. the mold is closed, the sodium borosilicate ispoured in through the gate 6 and is then compressed by means of atamping iron f or by a press.

When this casting process has been completed, the insulating body I) istaken out of thief mold and the surplus material I) is out o Y Theinsulating body I), provided with the axial electrode a, and while in aplastic state is then placed in a second metal twopart mold 9 (Figs. 4and 5), each member of which is furnished with a handle and fits oneagainst the other, and provided with an shell to the insulating body,and as the metal of the shell contracts, on cooling, more than thematerial of the insulating body, the shell is held in closecontact withthe said body'so that there is no possibility of leakage between theparts. Then again owing to the insulating body being hot when the shellis cast thereon, there is no likelihood of the insulating body beingbroken as would likely happen if the shell was cast on a cold insulatingbody.

As these two casting processes are effected while the -masses are hotduring the entire operation, it will readily be understood that,

after cooling, the three constituent parts of the plug will beintimately united so asto form a single structure.

The shape and dimensions. of the various members of the improved plug,as Well as the materials of which they are made, may be modified.

Claims 1. The herein described process for manufacturing spark plugs,for explosion motors consisting in casting a glass insulator on a metalrod which forms an electrode and then immediately While the insulator isin a plastic state, casting a metal shell on the insulator.

2. The herein described process for manufacturing spark plugs forexplosion motors, consisting in casting an insulating body formed ofborax-silicate upon a metal rod which forms an electrode, and thenimmediately While the insulator body is in a plasti'c state, casting ametal shell upon the insulator body.

3. The herein described process for manufacturing spark plugs forexplosion motors, consisting in casting an insulating body on a. metalrod which forms an electrode, and then immediately while the insulatingbody is in a plastic state, casting an alloy of zinc, aluminiumandfcopper on the insulating body.

he foregoing specification of my improved sparking plu forinternal-combustion engines and met 0d of manufacturing the same, signedby me this 27th day of J anuary 1919.

CHARLES EMILE GERBAUD.

